GET _alias/<alias> returns aliases for non-matching data streams

[sorenlouv]

Elasticsearch Version

8.9.0-SNAPSHOT

Installed Plugins

No response

Java Version

bundled

OS Version

MacOS 13.2.1 (arm64)

Problem Description

In 8.9.0-SNAPSHOT if a data stream my-data-stream is created and has the alias my-alias it is returned when running GET _alias/foobarbaz*.

My expectation is that only data streams starting with “foobarbaz” should be returned.

Steps to Reproduce

--
# Create index template
PUT _index_template/my-index-template
{
  "index_patterns": ["my-data-stream*"],
  "data_stream": { },
  "priority": 500
}

--
# Create data stream
PUT _data_stream/my-data-stream

--
# Create alias for data stream
POST _aliases
{
  "actions": [
    {
      "add": {
        "index": "my-data-stream",
        "alias": "my-alias"
      }
    }
  ]
}

--
# List aliases
GET _alias/foobarbaz*

This returns:

{
  "my-data-stream": {
    "aliases": {
      "my-alias": {}
    }
  }
}

Logs (if relevant)

No response

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[mattc58]

Just tested this on 8.11.3 and can reproduce. I ran the steps in the issue and got this result:

{
  "my-data-stream": {
    "aliases": {
      "my-alias": {}
    }
  }
}